I allow him to move past just a little/wait for his attention to be averted, pull the hammer back, BOOOMM! He may hear the "click" from 20 or 30, but probably not any farther than that if there is wind and other interference. By the time he turns his head to look its too late at that range. No need for a set trigger if he is 20 yards away, or even 50. I just never got into the habit of using it, and learned to shoot the gun without it.